Hermann thomas



(Model.)

H. THOMAS. PRGPELLBR SCREW;

' Patented Oct. 14, 1890.

WIT/VESSES:

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NITED STATES PATENT OFFICE.

VHERMANN THOMAS, OF NEV YORK, N. Y., ASSIGNOR OF ONE-FOURTH TO RUDOLPHSTUELER, OF SAME PLACE.

PROPELLER-SCREW.

SPECIFICATION forming part of Letters Patent No. 438,365, dated October14, 1890.

Application led .T une Z1, 1889. Serial No. 315,064. (Model.)

To @ZZ whom zit may concern:

Be itknown thatI, HERMANN THOMAS, of the city, county, and State of NewYork, a citizen of the Empire of Germany, haveinvented certain new anduseful Improvements in Propeller-Screws, of which the following is aspecification.

This invention relates to certain improvements inthe construction ofscrew-propellers for vessels by which a larger working-surface of theblades is obtained and a greatly-reduced quantity of material requiredfor the propeller, so that an increased working power is obtained, andconsequently a greater speed imparted to the vessel at a saving of fuel.

The invention consists of a screw-propeller in which each blade isformed of a leading or forward portion and a rear portion, which areunited at an obtuse angle with each other, and of which one represents aportion of the cylinder of a screw, while the other represents a threadof the screw, the leading portion cutting or separating the water like aknife, while the rear portion prevents the slipping off of the water,which is equally distributed over the entire surface of the blade. Theleading portion of each blade is extended over the hub so as to form adipping point or wing, which enters into the waterin advance of theblade proper. The working-surface of the blade is also increased at theperiphery of the same by enlarging the outer ends of the blades andarranging the outer edge in such a manner that every point of the saineis equidistant from the axis of the propeller. This effectively enlargesthe surface area 0f the blades and increases the working capacity of thepropeller. The hub to which the blades are attached is made of conicalshape, its diameter at the rear end being larger than the diameter atthe front end, so as to provide for the arrangement of the dipping-wingsand for retaining the water effectively around the surface of the hubwhen the propeller is rotated in opposite directions.

In the accompanying drawings, Figure l represents afront elevation of myimproved screw-propeller. Fig. 2 is a rear elevation 0f the same. Figs.3 and 4 are side elevations taken from opposite sides. Fig. 5 showsvertical transverse sections of different forms of the blades, taken online x, Fig. l and Figs. (i and 7 are diagrams, illustrating thetheoretical development of the blades.

Similar letters of reference indicate corresponding parts.

Referring to the drawings, A represents the hub, and B B the blades, ofmy improved screwpropeller. rally on the hub, the leading or forwardportion of each blade being arranged at a greater angle to the axis ofthe hub than the rear portion of said blade, and each portion having aspiral twist, which constantly increases the angle which each part formswith the axis of rotation as the distance from the hub increases. Eachblade is made of a leading portion a and a rear portion b, which arejoined to each other at an obtuse angle, as shown in Fig. 5, which angleremains constant throughout the length of the blade. Parts a b formtogether an effective working-surface,

the rear portion represent-inga portion of the cylinder of a screw whilethe leading portion represents the thread of a screw. The leadingportion a cuts or separates the water like a knife and in the sainemanner as the thread of a screw, while the body of water which is cut bythe same is prevented from slipping off by the rear part.

By the angle formed by the two portions a and b of the blade the wateris retained and equally distributed over the` entire surface of theblade. The friction of the water on the working-surfaces of the bladesis equalized as much as possible, as the surfaces of the blades in thedirection in which the water is cut are circular, and as they arejointed at all points at the same angle, whereby a reaction of the wateris made impossible and an easier and more effective working of thepropeller produced.

The leading portion of each blade is eX- tended inwardly and forwardlyover the hub A, so as to form a wing cl, which enters into the water inadvance of the leading portion of the blade, and by which the blade isenlarged at or near the hub, where the greatest working effect isproduced. The width of the blade is also increased at its outer end, asthe The blades B are arranged spi- IOO leading and rear portions a and bare continued nearly at their full width to the periphery of the blade,which periphery is so constructed that each point thereof is equidlstantfrom the axis 'of the screw. The working capacity of the blades isthereby greatly enhanced, owing to the increase in the working-surfaceof the blade, which is an essential advantage that is not found in anyother screw-propeller, and by which the screw-propeller is enabled toexert a greater propelling power. The enlargement of the blades by thedipping wings at the hub and by the widening of the blades at theperiphery has also the advantage of reducing the vibrations of thevessel caused by the oscillations of the screw-propellers, inasmuch asthe propeller is subgected by the easy cutting through the water and theclose hugging of the latter to the working-surfaces of the blades to asmaller amount of injurious strains and interfering influences. Thedipping wings on the hub also have the advantage that the main part ofthe work which the propeller has to perform is accomplished in closeproximity to the propeller-shaft, while the enlarged size of the bladesat the periphery counterbalances the enlargement produced by the wings.The

greatest width of the blades is arranged ati' mid-length of the same,from which their wid th 1s slightly decreased toward the periphery. 1 Theobtusely angled cross section of thef blades also gives a longersurface-connection v with the hub and increases the strength andresistance ofthe entire propeller to the water, as the front and rearparts of each blade strengthen each other, which gives to the blade agreat advantage for towing as well as for i The blades may be riveted orotherwise fastened to the hub, so that each l blade can be removed andreplaced by another y blades arranged spirally on the hub, the leadspeedpurposes.

or cast integral with the hub, as desired.

The hub A, to which the blades are attached,

is of conical shape and diminishes in size from its rear toward theforward end, so as to arrange for the forward-extending dipping` rotatedin opposite direction for backing the y vessel.

Having thus described my invention I claim as new and desire to secureby Letters Pat- 1 l. A screw-propeller having blades of obtusely-angledcross-section, said blades being extended at their inner front ends overthe hub so as to form dipping wings, substantially as set forth.

2. A screw-propeller having blades arranged spirally on the hub, theleading or forward portion of each blade'being arranged at a greaterangle to the axis of the hub than the rear portion of said blade, andthe front or cutting edge of each blade being inclined spirally rearwardfrom the front of the hub, all substantially as described.

8. A screw-propeller having blades Whose front or leading portion isunited to the rear portion thereof at an obtuse angle, which angleremains constant throughout the length of the blade, the leading portionbeing arranged at a greater angle to the axis of the hub than the rearportion thereof and 4each portion having a spiral twist,which constantlyincreases the angle which each part forms with the axis of rotation asthe distance from the hub increases, substantially as described.

4. A screw-propeller the blades of which are arranged spirally on thehub and formed of two portions which are united at an obtuse angle toeach other, the leading portion of each blade being extended over thehub at its inner end and the rear portion enlarged toward the periphery,so that the Width of each blade at the periphery is somewhat smallerthan the width of the blade at its center, whereby the working-surfacesof the'blade are enlarged toward the hub and periphery, substantially asset forth.

5. A screw-propeller composed of a conically-tapering hub and ofobtusely-angled blades extending from said hub, substantially as setforth.

G. A screw-propeller having obtusely-angled ing portion of each bladebeing arranged at a greater angle to the axis of the hub than the rearportion of said blade and extended at its inner end over the hub so asto form dipping wings, substantially as set forth.

In testimony that I claim the foregoing as my inventionl have signed myname in presence of two subscribing witnesses.

HERMANN THOMAS.

Witnesses:

PAUL GoEPEL, JOHN A. STRALEY.

ICO

